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<html>
  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
    <meta name='apple-mobile-web-app-capable' content='yes'>
    <link rel='icon' type='image/png' sizes='32x32' href='favicon-32x32.png'>
    <link rel='icon' type='image/png' sizes='96x96' href='favicon-96x96.png'>
    <link rel='stylesheet' href='css/common.css'>

    <title>Room Scale</title>
  </head>
  <body>
    <header>
      <details open>
        <summary>Room Scale</summary>
        <p>
          This sample demonstrates using a 'local-floor' reference space to provide
          room scale tracking.
          <a class="back" href="./">Back</a>
        </p>
      </summary>
    </header>
    <script type="module">
      import {WebXRButton} from './js/util/webxr-button.js';
      import {Scene} from './js/render/scenes/scene.js';
      import {Renderer, createWebGLContext} from './js/render/core/renderer.js';
      import {Gltf2Node} from './js/render/nodes/gltf2.js';
      import {SkyboxNode} from './js/render/nodes/skybox.js';
      import {BoundsRenderer} from './js/render/nodes/bounds-renderer.js';
      import {InlineViewerHelper} from './js/util/inline-viewer-helper.js';
      import {QueryArgs} from './js/util/query-args.js';

      // If requested, use the polyfill to provide support for mobile devices
      // and devices which only support WebVR.
      import WebXRPolyfill from './js/third-party/webxr-polyfill/build/webxr-polyfill.module.js';
      if (QueryArgs.getBool('usePolyfill', true)) {
        let polyfill = new WebXRPolyfill();
      }

      // XR globals.
      let xrButton = null;
      let xrImmersiveRefSpace = null;
      let inlineViewerHelper = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      scene.addNode(new Gltf2Node({url: 'media/gltf/camp/camp.gltf'}));
      scene.addNode(new SkyboxNode({url: 'media/textures/eilenriede-park-2k.png'}));
      scene.standingStats(true);

      let boundsRenderer = null;

      function initXR() {
        xrButton = new WebXRButton({
          onRequestSession: onRequestSession,
          onEndSession: onEndSession
        });
        document.querySelector('header').appendChild(xrButton.domElement);

        if (navigator.xr) {
          navigator.xr.isSessionSupported('immersive-vr').then((supported) => {
            xrButton.enabled = supported;
          });

          navigator.xr.requestSession('inline').then(onSessionStarted);
        }
      }

      function onRequestSession() {
        return navigator.xr.requestSession('immersive-vr', {
            // Our standing experience will require at least a local-floor
            // reference space (which will be available even on 3DoF device)
            // but can optionally make use of bounded-floor reference spaces
            // when available.
            requiredFeatures: ['local-floor'],
            optionalFeatures: ['bounded-floor']
        }).then((session) => {
          xrButton.setSession(session);
          session.isImmersive = true;
          onSessionStarted(session);
        });
      }

      function initGL() {
        if (gl)
          return;

        gl = createWebGLContext({
          xrCompatible: true
        });
        document.body.appendChild(gl.canvas);

        function onResize() {
          gl.canvas.width = gl.canvas.clientWidth * window.devicePixelRatio;
          gl.canvas.height = gl.canvas.clientHeight * window.devicePixelRatio;
        }
        window.addEventListener('resize', onResize);
        onResize();

        renderer = new Renderer(gl);

        scene.setRenderer(renderer);
      }

      function onSessionStarted(session) {
        session.addEventListener('end', onSessionEnded);

        initGL();

        let glLayer = new XRWebGLLayer(session, gl);
        session.updateRenderState({ baseLayer: glLayer });

        function onRefSpaceCreated(refSpace) {
          if (session.isImmersive) {
            xrImmersiveRefSpace = refSpace;
          } else {
            // If we're using a viewer reference space we need to scoot the
            // origin down a bit to put the camera at approximately the right
            // level. (Here we're moving it 1.6 meters, which is *very* roughly
            // the eye height of an "average" adult human.)
            inlineViewerHelper = new InlineViewerHelper(gl.canvas, refSpace);
            inlineViewerHelper.setHeight(1.6);

            // You can accomplish the same thing without the helper class by
            // simply offseting the reference space with a negative y value:
            // refSpace = refSpace.getOffsetReferenceSpace(new XRRigidTransform({y: -1.6}));
          }
          session.requestAnimationFrame(onXRFrame);
        }

        if (session.isImmersive) {
          // Attempt to get a 'bounded-floor' reference space, which will align
          // the user's physical floor with Y=0 and provide boundaries that
          // indicate where the user can safely walk.
          session.requestReferenceSpace('bounded-floor').then((refSpace) => {
            onRefSpaceCreated(refSpace);

            if (!boundsRenderer) {
              boundsRenderer = new BoundsRenderer(refSpace);
              scene.addNode(boundsRenderer);
            } else {
              boundsRenderer.boundedRefSpace = refSpace;
            }

            refSpace.onreset = (evt) => {
              boundsRenderer.boundedRefSpace = evt.referenceSpace;
            }
          }).catch(() => {
            // If a bounded reference space isn't supported, fall back to a
            // local-floor reference space. This still provides a floor-relative
            // space and will always be supported for immersive sessions. It
            // will not, however, provide boundaries and generally expects the
            // user to stand in one place. If the device doesn't have a way of
            // determining the floor level (for example, with a 3DoF device)
            // then it will return an emulated local-floor space, where the view
            // is translated up by a static height so that the scene still
            // renders in approximately the right place.
            console.log('Falling back to local-floor reference space');
            session.requestReferenceSpace('local-floor').then(onRefSpaceCreated);
          });
        } else {
          session.requestReferenceSpace('viewer').then(onRefSpaceCreated);
        }
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        if (event.session.isImmersive) {
          xrButton.setSession(null);
        }
      }

      function onXRFrame(t, frame) {
        let session = frame.session;
        let refSpace = session.isImmersive ?
                         xrImmersiveRefSpace :
                         inlineViewerHelper.referenceSpace;
        let pose = frame.getViewerPose(refSpace);

        scene.startFrame();

        session.requestAnimationFrame(onXRFrame);

        // Every XR frame uses basically the same render loop, so for the sake
        // of keeping the sample code focused on the interesting bits most
        // samples after this one will start using this helper function to hide
        // away the majority of the rendering logic.
        scene.drawXRFrame(frame, pose);

        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>
